#define _CRT_SECURE_NO_WANINGS 1
#pragma warning(disable: 4996)

class Solution {
public:
    bool CheckPermutation(string s1, string s2) {
        int ret = 0, jud1 = 0, jud2 = 0;
        if (s1.size() != s2.size()) return false;

        for (int i = 0; i < s1.size(); i++) {
            ret ^= s1[i];
            ret ^= s2[i];
        }
        return ret == 0;
    }
};